Knowing what to expect—and what an "average" penis size really Age 10 to 11 : 1.6 to 3.1 inches; Age 12: 2.0 to 4.0 inches; Age 13: 2.0 to 4.7.
An average penis size of 8.8 cm (3.5 inches) when flaccid, An average penis size of 12.9 cm (5.1 inches) when erect is seen as normal.
Usually by the end of puberty, a guy's penis has reached its expected size. Puberty usually ends about 4 years after it starts, so this is usually around age 13 –19.
Oh, man. I remember being your age and being concerned about my penis size. I had the distinct disadvantage in this area of being homeschooled. I didn't have.